Shelf



FIG. 1 is a front elevational view of a shelf showing my new design, the rear being unornamented and following the contour shown at left of FIG. 2;

FIG. 2 is a side elevational view thereof, the opposite side being a mirror image;

FIG. 3 is a top plan view thereof, the bottom being unornamented and following the contour shown at the bottom of FIGS. 1 and 2; and,

Fig. 4 is a perspective view thereof. 

The ornamental design for a shelf, as shown and described. 